Data Validation Techniques

In this chapter, you will learn about using JavaScript to validate data entered by the user or coming from other systems. You already heard a lot about this in Chapter 2, which dealt with decisions involving data, and we will use some of that knowledge and extend it here.

Data validation has gone though some changes with the introduction of HTML5. Before, JavaScript was the first line of defense against having bad data possibly sent to the database. Now new features built into the browser help developers by removing a lot of the heavy lifting because the browser does a large part of the validation itself. ...

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